Frame error identification

1. A method of identifying errors in a data frame transmitted via a cellular network from a first mobile station to a second mobile station different from the first mobile station, comprising the first mobile station performing the steps of: generating an uplink error check code for a data frame for uplink transmission; and transmitting the data frame and its associated uplink error check code to the network; the network performing the steps of: determining the quality of the received data frame; generating a downlink error check code for the received data frame, if the received frame quality is good, on the basis of the received data frame, and if the received frame quality is bad, on the basis of a function of the received data and a parameter indicative of the quality of the received data frame; and transmitting the data frame and the associated downlink error check code to the second mobile station; the second mobile station performing the steps of: decoding the received data frame and the associated downlink error check code; and determining if the received data frame and the associated downlink error check code represent a good quality data frame.

2. A method of identifying errors in a data frame transmitted via a cellular network from a first mobile station to a second mobile station different from the first mobile station, comprising the first mobile station performing the steps of: generating an uplink error check code for a data frame for uplink transmission; and transmitting the data frame and its associated uplink error check code to the network; the network performing the steps of: determining the quality of the received data frame; generating a downlink error check code for the received data frame, if the received frame quality is good, on the basis of a first function of the received data frame and a first parameter indicative of the received frame quality, and if the received frame quality is bad, on the basis of a second function of the received data and a second parameter indicative of the quality of the received data frame quality; and transmitting the data frame and the associated downlink error check code to the second mobile station; the second mobile station performing the steps of: decoding the received data frame and the associated downlink error check code; and determining if (i) the received data frame, having the inverse of the first function applied thereto, and the associated downlink check code, or (ii) the received data frame, having the inverse of the second function applied thereto, and the associated downlink check code, represent a good quality data frame.

3. A method of identifying errors in a data frame transmitted via a cellular network from a first mobile station to a second mobile station different from the first mobile station, comprising the first mobile station performing the steps of:— generating an uplink error check code for a data frame for uplink transmission; and transmitting the data frame and its associated uplink error check code to the network; the network performing the steps of: determining the quality of the received data frame; generating a downlink error check code for the received data frame and, if the received data frame quality is good, modifying the error check code in accordance with a first operation, and if the received data frame quality is bad, modifying the error check code in accordance with a second operation; and transmitting the data frame and its associated modified error check code to the second mobile station; the second mobile station performing the steps of: decoding the received data frame and the associated downlink error check code; and determining if (i) the received data frame and the associated downlink check code, having the first operation applied in reverse thereto, or (ii) the received data frame and the associated downlink check code, having the second operation applied in reverse thereto, represent a good quality data frame.

4. A method of identifying errors in an over-the-air transmission of a data frame having associated frame quality information, wherein a first station performs the steps of: generating a transmission error check code based on the data frame to be transmitted in combination with its associated frame quality information; transmitting the data frame, absent the frame quality information, and the transmission error check code; and a second station different than the first station performs the steps of: decoding the transmitted data frame and the transmission error check code; generating a pseudo error check code based on the decoded data frame and frame quality information indicative of a good data frame; and comparing the decoded transmission error check code and the pseudo error check code.